How do i get a function from a data on matlab and generate a signal from it

i have a set of time-based data, and i want to generate a signal and a function from it, how did i do this?

my data is :

t(0) = 0
t(1/2r) = root(1/2)*r
t(r) = r
r((1+1/2)r) = root(1/2)*r
t(2r) = 0
t((2+1/2)r) = -root(1/2)*r
t(3r) = -r
t((3+1/2)r) = -root(1/2)*r
t(4r) = 0

i wanted to generate a function from these input and create a signal plot from it,

[Guillaume]

What you call data does not use valid matlab syntax, so it's unclear what you mean by data.

For that matter it's not clear what you call a function and a signal.